A Complex Distribution of Elongation Family GTPases EF1A and EFL in Basal Alveolate Lineages

Translation elongation factor-1 alpha (EF1A) and the related GTPase EF-like (EFL) are two proteins with a complex mutually exclusive distribution across the tree of eukaryotes. Recent surveys revealed that the distribution of the two GTPases in even closely related taxa is frequently at odds with their phylogenetic relationships. Here, we investigate the distribution of EF1A and EFL in the alveolate supergroup. Alveolates comprise three major lineages: ciliates and apicomplexans encode EF1A, whereas dinoflagellates encode EFL. We searched transcriptome databases for seven early-diverging alveolate taxa that do not belong to any of these groups: colpodellids, chromerids, and colponemids. Current data suggest all seven are expected to encode EF1A, but we find three genera encode EFL: Colpodella, Voromonas, and the photosynthetic Chromera. Comparing this distribution with the phylogeny of alveolates suggests that EF1A and EFL evolution in alveolates cannot be explained by a simple horizontal gene transfer event or lineage sorting.